In U.S. Pat. No. 3,898,140, the disclosure of which is incorporated herein by reference, it is disclosed that in a process for hydrodimerizing an olefinic nitrile, amide or ester by electrolyzing an aqueous solution containing the olefinic starting material and a conductive salt, formation of molecular hydrogen at the cathode can be substantially inhibited and the current efficiency of the process can be significantly increased by including in the solution a nitrilocarboxylic acid compound such as, for example, a salt of ethylenediaminetetraacetic acid or N-hydroxyethylethylenediaminetriacetic acid. Although the process improvements described in U.S. Pat. No. 3,898,140 are an important advance in the art, even further improvements whereby such hydrogen formation can be even more fully inhibited and the current efficiency of the process can be even further increased are manifestly highly desirable, and it is an object of this invention to provide such further process improvements. Additional objects of this invention will be apparent from the following description and examples in which all percentages are by weight except where otherwise noted.